Premiere newbie needs help...

I am new to Adobe Premiere 6.0. I have a clip in the Video 2 slot on my timeline. I am using the Opacity Rubberband to create a fadeout at the end of my clip. I export of the timeline, and at the point of my fadeout the video image size changes to a reduced size during playback. During the preview in the Monitor window there is no size change or fadeout affects. The fadeout I can understand, but I cannot seem to figure out what is going on with the size change. Any ideas?